The present invention relates to a display panel such as plasma display panel (hereinafter, referred to as xe2x80x9cPDPxe2x80x9d). The present invention further relates to a method of manufacturing an electromagnetic-wave shielding and light transmitting plate to be used as a front filter for a PDP, and windows of building which need electromagnetic wave shielding, such as a hospital.
PDPs (plasma display panels) utilizing discharge phenomenon have been researched and developed as display panels for television sets, office automation apparatuses such as personal computers and word processors, traffic control signs, signboards, and other display boards.
A PDP includes two glass plates, a large number of discharge cells formed by partitions between the two glass plates, and fluorescent substances within the respective discharge cells. The fluorescent substances are selectively excited to emit light by discharge, thereby displaying characters and/or figures. As shown in FIG. 3, such a PDP comprises a front glass 21, a rear glass 22, partitions 23, display cells (discharge cells) 24, auxiliary cells 25, cathodes 26, display anodes 27, and auxiliary anodes 28. Disposed in each display cell 24 is a red, green, or blue fluorescent substance (not shown) which is a film-like form attached to the inside thereof. These fluorescent substances emit light by electrical discharges when a voltage is applied between electrodes.
From the front surface of the PDP, electromagnetic waves with frequency from several kHz to several GHz are generated due to applying voltage, electrical discharge, and light emission. The electromagnetic waves are required to be shielded. In addition, for improving its display contrast, reflection of external light at the front surface is required to be prevented.
In order to shield such electromagnetic waves from PDP, a transparent plate which has electromagnetic-wave shielding property is disposed in front of the PDP.
As an electromagnetic-wave shielding material for an electromagnetic-wave shielding and light transmitting,plate, a conductive mesh member is employed which is a 5- to 500-mesh member having a line width from 10 to 500 xcexcm and an open area ratio (open area percentage) less than 75%.
The electromagnetic-wave shielding plate having such a conductive mesh member with low open area ratio as mentioned above has light transmitting property of 70% at the most. Moreover, conventional conductive mesh members easily allow the production of moire patterns due to relations between its patterns and pixel pitch.
JP H11-204045A discloses a display panel comprising a plasma display panel and a transparent substrate bonded to a front of the plasma display panel by transparent adhesives. The display panel has a conductive layer on a bonding surface of the transparent substrate which is made of conductive ink or paste by pattern printing and formed in a lattice with a line width of 200 xcexcm or less and an open area ratio of 75% or more.
In the display panel, the PDP and the transparent substrate formed with the conductive layer are integrated together by transparent adhesives as mentioned, thereby lightening its weight, making it""s thickness thinner, reducing the number of parts, and thus improving the productivity and reducing the cost.
The pattern printing enables the formation of a conductive layer into a lattice having high open area ratio while having narrow line width, that is, a line width of 200 xcexcm or less and an open area ratio of 75% or more. Such a conductive layer having high open area ratio and narrow line width has excellent light transmission properties and can prevent the moire phenomenon.
It should be noted that the term xe2x80x9copen area ratioxe2x80x9d is calculated from the line width of the mesh and the number of lines existing in one-inch width.
Employed as the conductive ink mentioned above is binder resin (ink medium) in which conductive particles are dispersed. The conductive ink needs to have high viscosity to keep the dispersed state of conductive particles in the conductive ink. Therefore, it is impossible to make the line width of the printed pattern of the conductive ink significantly narrow and also impossible to make the open area ratio significantly high.
It is an object of the present invention to provide a display panel in which an electromagnetic-wave shielding material formed with a conductive pattern is disposed on and integrated with the front surface of the display panel, wherein the conductive pattern is in a mesh-like form having an enough small line width and significantly high open area ratio.
It is another object of the present invention to provide a method of manufacturing an electromagnetic-wave shielding and light transmitting plate formed with a mesh-shaped conductive pattern having an enough small line width and significantly high open area ratio.
A display panel of the present invention comprises: a display panel body, a transparent film disposed on a front surface of the display panel body, and a conductive pattern formed on the transparent film. The conductive pattern is a mesh-like pattern composed of a vapor plated layer or a liquid phase plated layer.
The display panel can achieve improvement of the productivity and reduction in the cost because the display panel comprises the display panel body and the transparent film formed with a conductive pattern, thereby lightening its weight, making its thickness thinner, reducing the number of parts.
The conductive pattern is manufactured according to the method of manufacturing an electromagnetic-wave shielding and light transmitting plate of the present invention, comprising a step of forming dots of material which is soluble in solvent on a film surface, a step of forming a conductive material layer which is insoluble in the solvent on the film surface by a vapor plating or a liquid phase plating, and a step of removing the dots and portions of the conductive material layer on the dots by bringing the film surface in contact with the solvent.
According to this manufacturing method, the material which is soluble in the solvent has no conductive particles dispersed therein. Therefore, the dots can be printed or formed by using the material having low viscosity. Therefore, fine and precision printing can be achieved in such a manner as to form significantly narrow spaces defined by the dots. Since the narrow spaces between the dots are areas on which conductive material is left to form a mesh-like conductive pattern, the conductive pattern having significantly fine line width can be formed with high accuracy. By reducing the line width, the open area ratio of the mesh can be greater.
According to the present invention, it is preferable that the conductive pattern is a conductive mesh pattern having a line width of 50 xcexcm or less and an open area ratio of 75% or more. The conductive pattern having narrower line width and greater open area ratio can exhibit excellent light transmission properties and prevent the moire phenomenon.